This was a multi-center, open-label, dose escalation Phase I trial designed to test the safety, pharmacokinetics, and preliminary biologic activity of BMS-188667 (CTLA4Ig) administered as four intravenous injections on Days 1, 3, 16, and 29 to patients with psoriasis vulgaris. The major goals of this study were the determination of: the safety, pharmacokinetics, immunogenicity, and recovery time from biological effects and optimal biologic dose for psoriasis treatment of Bms-188667.